Dual directional asymmetric coupler with a shared through-line

Abstract

A reflectometer may include two directional couplers in a parallel configuration, sharing the same section of a signal line or through-line. For example, two directional couplers may be disposed across from each other on opposite sides of the shared through-line. One of the directional couplers may couple, to a first port of the reflectometer, a portion of the signal power of a first signal flowing from the first end of the shared through-line to the second end of the shared through-line, and the other directional coupler may couple, to a second port of the reflectometer, a portion of the signal power of a second signal flowing from the second end of the shared through-line to the first end of the shared through-line. The reflectometer benefits from reduced size and signal loss with respect to reflectometers having a serial configuration. When used in vector network analyzer (VNA) systems, this results in higher output power and higher dynamic range of the VNA.

We claim: 
     
       1. A reflectometer comprising:
 a first port and a second port; and 
 a first directional coupler and a second directional coupler configured to share a section of a signal line by being disposed across from each other on opposite sides of the signal line, the signal line having a first end and a second end; 
 wherein the first directional coupler is configured to couple, to the first port, at least a portion of signal power of a first signal flowing from the first end through the shared section of the signal line to the second end; 
 wherein the second directional coupler is configured to couple, to the second port, at least a portion of signal power of a second signal flowing from the second end through the shared section of the signal line to the first end; and 
 wherein a physical length of the reflectometer is one-half of a wavelength of a lowest operating corner frequency of the reflectometer. 
 
     
     
       2. The reflectometer of  claim 1 , further comprising:
 a third port and a fourth port each configured with a respective termination having an impedance that minimizes reflections at the respective termination. 
 
     
     
       3. The reflectometer of  claim 1 , wherein the first port and the second port are configured to couple to respective receivers. 
     
     
       4. The reflectometer of  claim 1 , wherein the first port, the second port, the first directional coupler, and the second directional coupler are configured on a printed circuit board. 
     
     
       5. The reflectometer of  claim 4 , wherein components of the first directional coupler are configured on first circuit layers of the printed circuit board, and components of the second directional coupler are configured on one of:
 the first circuit layers; or 
 second circuit layers of the printed circuit board, wherein the second circuit layers are one of:
 different from the first circuit layers; or 
 partially the same as the first circuit layers. 
 
 
     
     
       6. The reflectometer of  claim 1 , wherein the signal line is comprised in a measurement instrument. 
     
     
       7. The reflectometer of  claim 6 , wherein the measurement instrument is a vector network analyzer. 
     
     
       8. A measurement system comprising:
 a signal line coupling a signal port to a test port; and 
 a first directional coupler and a second directional coupler disposed across from each other on opposite sides of the signal line to share a section of the signal line; 
 wherein the first directional coupler is configured to couple, to a first port, at least a portion of signal power of a first signal flowing from the signal port to the test port; 
 wherein the second directional coupler is configured to couple, to a second port, at least a portion of signal power of a second signal flowing from the test port to the signal port; and 
 wherein a physical length of the section of the signal line is one-half of a wavelength of an operating corner frequency of the reflectometer. 
 
     
     
       9. The measurement system of  claim 8 , further comprising:
 a third port coupled to the first port via a first line; and 
 a fourth port coupled to the second port via second line; 
 wherein the third port and the fourth port are each terminated with a characteristic impedance of the measurement system. 
 
     
     
       10. The measurement system of  claim 8 , wherein the first port and the second port are coupled to respective receivers. 
     
     
       11. The measurement system of  claim 8 , wherein the first directional coupler and the second directional coupler are configured on a printed circuit board. 
     
     
       12. The measurement system of  claim 8 , wherein the signal line is comprised in a vector network analyzer. 
     
     
       13. A vector network analyzer (VNA) system comprising:
 one or more signal ports; 
 one or more test ports respectively coupling to the one or more signal ports via respective signal lines; and 
 one or more reflectometers respectively corresponding to the respective signal lines, wherein each respective reflectometer of the one or more reflectometers corresponds to a respective signal line of the respective signal lines and comprises:
 a first port and a second port; and 
 a first directional coupler and a second directional coupler disposed across from each other on opposite sides of the respective signal line to share a section of the respective signal line; 
 wherein the first directional coupler is configured to couple, to the first port, at least a portion of signal power of a first signal flowing from the signal port of the respective signal line to the test port of the respective signal line through the shared section of the respective signal line; 
 wherein the second directional coupler is configured to couple, to the second port, at least a portion of signal power of a second signal flowing from the test port of the respective signal line to the signal port of the respective signal line through the shared section of the respective signal line; and 
 wherein for each respective reflectometer, a physical length of the respective reflectometer is one-half of a wavelength of a lowest operating corner frequency of the respective reflectometer. 
 
 
     
     
       14. The VNA system of  claim 13 , wherein each respective reflectometer further comprises:
 a third port coupled to the first port via a first line; and 
 a fourth port coupled to the second port via second line; 
 wherein the third port and the fourth port are each configured with a respective termination having an impedance that minimizes signal reflections at the respective termination. 
 
     
     
       15. The VNA system of  claim 14 , wherein each respective reflectometer is configured to reduce a coupling between a respective coupling line of its first directional coupler and a respective coupling line of its second directional coupler. 
     
     
       16. The VNA system of  claim 13 , further comprising:
 one or more first receivers, wherein each respective first receiver of the one or more first receivers is coupled to the first port of a respective corresponding reflectometer; and 
 one or more second receivers, wherein each respective second receiver of the one or more second receivers is coupled to the second port of the respective corresponding reflectometer. 
 
     
     
       17. The VNA system of  claim 13 , wherein each respective reflectometer of the one or more reflectometers is configured on a printed circuit board. 
     
     
       18. The VNA system of  claim 17 , wherein for each respective reflectometer of the one or more reflectometers:
 components of the first directional coupler are configured on first circuit layers of the printed circuit board, and components of the second directional coupler are configured on one of:
 the first circuit layers; or 
 second circuit layers of the printed circuit board, wherein the second circuit layers are one of:
 different from the first circuit layers; or 
 partially the same as the first circuit layers. 
 
 
 
     
     
       19. The measurement system of  claim 11 , wherein components of the first directional coupler are configured on first circuit layers of the printed circuit board, and components of the second directional coupler are configured on one of:
 the first circuit layers; or 
 second circuit layers of the printed circuit board, wherein the second circuit layers are one of:
 different from the first circuit layers; or 
 partially the same as the first circuit layers. 
 
 
     
     
       20. The measurement system of  claim 8  further comprising a vector network analyzer, wherein the signal line is comprised in the vector network analyzer.